1. Field of the Invention
The present invention relates to a heat-insulating bearing structure.
2. Description of Related Art
A turbine that is revolved by high-temperature gas or a pump that is rotated to discharge high-temperature gas generally employs a structure including a rotary shaft provided with, at one end thereof, an impeller that directly comes into contact with the high-temperature gas and a rolling bearing that rotatably supports the rotary shaft. For example, Japanese Unexamined Patent Application Publication No. 2007-9702 discloses a structure that prevents a temperature increase of the rolling bearing by arranging a water-cooling jacket around the rotary shaft and circulating cooling water through the jacket to cool the periphery of the rotary shaft.
Such a related art that employs the water-cooling jacket for cooling the periphery of a rotary shaft is sometimes unable to secure a sufficiently large cooling area due to the structure of a turbine or pump for which the jacket is provided.
A solar heat utilization field of recent years condenses sunlight to produce high-temperature gas of 1000 degrees centigrade or over, and to transfer the high-temperature gas to a given location, requires a pump that is capable of resisting high temperatures. If such a pump adopts the water-cooling jacket for a whole cooling scheme, the jacket must be too complicated. It is required, therefore, to provide a bearing structure with a novel heat-resistant structure that does not rely on coolant.
To meet the requirement, the present invention is able to provide a heat-insulating bearing structure capable of surely supporting, without relying on water cooling, a rotary shaft of an impeller that comes into contact with high-temperature gas.